U.S. patent application number 15/674870 was filed with the patent office on 2019-02-14 for systems for battery charging using a wireless charging signal.
The applicant listed for this patent is Lion Semiconductor Inc.. Invention is credited to Wonyoung Kim, Aaron Melgar, Hans Meyvaert.
Application Number | 20190052113 15/674870 |
Document ID | / |
Family ID | 65271829 |
Filed Date | 2019-02-14 |
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United States Patent
Application |
20190052113 |
Kind Code |
A1 |
Melgar; Aaron ; et
al. |
February 14, 2019 |
SYSTEMS FOR BATTERY CHARGING USING A WIRELESS CHARGING SIGNAL
Abstract
Systems for charging a battery are provided, the systems
comprising: a regulator having an output coupled to the battery and
having an input; a wireless charging receiver having an output
coupled to the input of the regulator and having an input that
receives a power signal from a wireless charging transmitter; a
controller having a first input coupled to the input of the
regulator, having a second input coupled to the output of the
regulator, and having a first output coupled to the wireless
charging transmitter, wherein the controller is configured to send,
using the first output of the controller, a control signal to the
wireless charging transmitter that causes the wireless charging
transmitter to change the power signal provided to the wireless
charging receiver.
Inventors: |
Melgar; Aaron; (San Martin,
CA) ; Kim; Wonyoung; (Mountain View, CA) ;
Meyvaert; Hans; (Oakland, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lion Semiconductor Inc. |
San Francisco |
CA |
US |
|
|
Family ID: |
65271829 |
Appl. No.: |
15/674870 |
Filed: |
August 11, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 50/00 20160201;
H02J 7/00034 20200101; H02J 7/025 20130101; H02J 50/80 20160201;
H04B 5/0037 20130101; H02J 50/10 20160201 |
International
Class: |
H02J 7/02 20060101
H02J007/02; H02J 50/80 20060101 H02J050/80; H04B 5/00 20060101
H04B005/00; H02J 50/10 20060101 H02J050/10 |
Claims
1. A system for charging a battery, comprising: a regulator having
an output coupled to the battery and having an input; a wireless
charging receiver having an output coupled to the input of the
regulator and having an input that receives a power signal from a
wireless charging transmitter; a controller having a first input
coupled to the input of the regulator, having a second input
coupled to the output of the regulator, and having a first output
coupled to the wireless charging transmitter, wherein the
controller is configured to send, using the first output of the
controller, a control signal to the wireless charging transmitter
that causes the wireless charging transmitter to change the power
signal provided to the wireless charging receiver.
2. The system of claim 1, wherein the control signal causes the
wireless charging transmitter to change at least one of an
amplitude and a frequency of an AC voltage on an inductor of the
wireless charging transmitter that is inductively coupled to an
inductor of the wireless charging receiver.
3. The system of claim 1, wherein the control signal causes a
voltage output by the output of the wireless charging receiver to
change.
4. The system of claim 1, wherein the control signal causes the
voltage output by the output of the wireless charging receiver to
increase by a step amount.
5. The system of claim 1, wherein the control signal causes the
voltage output by the output of the wireless charging receiver to
decrease by a step amount.
6. The system of claim 1, wherein the regulator includes a switched
capacitor regulator, and wherein the control signal causes the
voltage output by the output of the wireless charging receiver to
change to a voltage that is an integer multiple of a voltage output
by the output of the regulator.
7. The system of claim 1, wherein the controller measures a first
measured voltage at the first input and measures a second measured
voltage at the second input.
8. The system of claim 7, wherein the controller sends the control
signal based upon a ratio of the first measured voltage to the
second measured voltage.
9. The system of claim 8, wherein the controller sends the control
signal based upon the ratio being greater than a value.
10. The system of claim 9, wherein the value is a threshold about
more than a conversion factor of the regulator.
11. The system of claim 1, wherein the controller has a second
output coupled to the regulator that causes the regulator to switch
modes.
12. The system of claim 11, wherein the controller causes the
regulator to change from a first conversion mode of the regulator
to a second conversion mode of the regulator.
13. The system of claim 12, wherein the first conversion mode of
the regulator has a different conversion factor that the second
conversion mode of the regulator.
14. The system of claim 1, wherein the first output of the
controller is wirelessly coupled to the wireless charging
transmitter.
15. The system of claim 1, wherein the first output of the
controller is wirelessly coupled to the wireless charging
transmitter using the wireless charging receiver.
16. The system of claim 1, wherein the input of the regulator is
also coupled to an adapter port configured to be coupled to a wired
charging adapter.
17. The system of claim 16, wherein the controller determines
whether a wired charging adapter is coupled to the adapter port,
and when the controller determines that a wired charging adapter is
coupled to the adapter port, the controller controls an output
voltage provided by the adapter.
18. The system of claim 16, wherein the controller controls the
output voltage provided by the adapter to be an integer multiple of
a voltage provided at the output of the regulator.
19. The system of claim 16, wherein the input of the regulator is
coupled to the wireless charging receiver by a switch.
20. The system of claim 16, wherein the input of the regulator is
coupled to the adapter port by a switch.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to apparatuses, systems, and
methods for charging a battery.
BACKGROUND
[0002] There is a strong demand to reduce the size of electronic
systems. Size reduction is especially desirable in mobile
electronics in which space is a premium, but is also desirable in
servers that are placed in big data centers since it is important
to squeeze in as many servers as possible into fixed-size real
estate.
[0003] Some of the largest components in electronic systems are
voltage regulators (also referred to as power regulators). Voltage
regulators often include a large number of bulky off-chip
components to deliver voltages to integrated chips, including
processors, memory devices (e.g., a dynamic random access memory
(DRAM)), radio-frequency (RF) chips, WiFi combo chips, and power
amplifiers. Therefore, it is desirable to reduce the size of
voltage regulators in electronic systems.
[0004] Voltage regulators include semiconductor chips, such as
DC-DC regulator chips, that each deliver power from a power source
(e.g., a battery) to an output load. The output load can include a
variety of integrated chips (e.g., an application processor, a
DRAM, a NAND flash memory, etc.) in an electronic device.
[0005] To efficiently deliver power, a voltage regulator can use a
"buck" topology. Such a regulator can be referred to as a buck
regulator (also referred to as a buck converter). A buck regulator
transfers charge from a power source to an output load using an
inductor. A buck regulator can use power switches to rapidly
connect/disconnect an inductor to/from multiple voltages (each at a
different point in time), thereby providing an output voltage that
is a weighted average of the multiple voltages. A buck regulator
can adjust the output voltage by controlling the amount of time the
inductor is connected to each of the multiple voltages.
[0006] Unfortunately, a buck regulator is not suitable for highly
integrated electronic systems. The conversion efficiency of a buck
regulator depends on the size of its inductor, in particular when
the power conversion ratio is high and when the amount of current
consumed by its output load is high. Because an inductor can occupy
a large area and is bulky to integrate on-die or on-package,
existing buck regulators often use a large number of off-chip
inductor components. This strategy often requires a large area on a
printed circuit board on which an existing buck regulator and its
corresponding off-chip inductor components are located, which in
turn increases the size of an electronic device in which the
printed circuit board is located. The challenge is exacerbated as
mobile system-on-chips (SoCs) become more complex and need
increasingly larger number of voltage domains to be delivered by
their voltage regulators.
[0007] Furthermore, a buck regulator is not well suited for
high-speed charging of a battery. High-speed charging generally
requires the use of a high input voltage. The use of a high input
voltage, in turn, requires the buck regulator to provide a high
voltage conversion ratio (V.sub.IN/V.sub.OUT) to convert a high
input voltage (V.sub.IN) to an output voltage (V.sub.OUT) that is
suitable for batteries. Unfortunately, at a high voltage conversion
ratio, the efficiency of the buck regulator is relatively low when
compared to other types of voltage regulators, at least in part
because the buck regulator wastes a large amount of power through
heat dissipation. The heat dissipated by a buck regulator may raise
the operating temperature of devices within an electronic system,
which could cause malfunctioning. Therefore, buck regulators are
not well suited for high-speed charging of batteries.
[0008] Instead of a buck regulator, a high-speed charging system
may use a switched-capacitor regulator to charge a battery. A
switched capacitor regulator is known to be efficient even at a
high voltage conversion ratio as long as the voltage conversion
ratio is an integer number. Unfortunately, existing charging
systems do not include a mechanism for keeping the conversion ratio
of a switched capacitor regulator at an integer number, and hence,
the high efficiency of a switched capacitor regulator cannot be
maintained across operating conditions. Therefore, there is a
strong need to provide a charging system that is capable of
maintaining a high efficiency at high input to output conversion
ratios.
SUMMARY
[0009] Systems for systems for battery charging using wireless
charging signals are provided. In some embodiments, systems for
charging a battery are provided, the systems comprising: a
regulator having an output coupled to the battery and having an
input; a wireless charging receiver having an output coupled to the
input of the regulator and having an input that receives a power
signal from a wireless charging transmitter; a controller having a
first input coupled to the input of the regulator, having a second
input coupled to the output of the regulator, and having a first
output coupled to the wireless charging transmitter, wherein the
controller is configured to send, using the first output of the
controller, a control signal to the wireless charging transmitter
that causes the wireless charging transmitter to change the power
signal provided to the wireless charging receiver.
[0010] In some of these embodiments, the control signal causes the
wireless charging transmitter to change at least one of an
amplitude and a frequency of an AC voltage on an inductor of the
wireless charging transmitter that is inductively coupled to an
inductor of the wireless charging receiver.
[0011] In some of these embodiments, the control signal causes a
voltage output by the output of the wireless charging receiver to
change.
[0012] In some of these embodiments, the control signal causes the
voltage output by the output of the wireless charging receiver to
increase by a step amount.
[0013] In some of these embodiments, the control signal causes the
voltage output by the output of the wireless charging receiver to
decrease by a step amount.
[0014] In some of these embodiments, the regulator includes a
switched capacitor regulator, and wherein the control signal causes
the voltage output by the output of the wireless charging receiver
to change to a voltage that is an integer multiple of a voltage
output by the output of the regulator.
[0015] In some of these embodiments, the controller measures a
first measured voltage at the first input and measures a second
measured voltage at the second input.
[0016] In some of these embodiments, the controller measures a
first measured voltage at the first input and measures a second
measured voltage at the second input, and sends the control signal
based upon a ratio of the first measured voltage to the second
measured voltage.
[0017] In some of these embodiments, the controller measures a
first measured voltage at the first input and measures a second
measured voltage at the second input, and sends the control signal
based upon a ratio of the first measured voltage to the second
measured voltage being greater than a value.
[0018] In some of these embodiments, the value is a threshold about
more than a conversion factor of the regulator.
[0019] In some of these embodiments, the controller has a second
output coupled to the regulator that causes the regulator to switch
modes.
[0020] In some of these embodiments, the controller has a second
output coupled to the regulator that causes the regulator to switch
modes and the controller causes the regulator to change from a
first conversion mode of the regulator to a second conversion mode
of the regulator.
[0021] In some of these embodiments, the controller has a second
output coupled to the regulator that causes the regulator to switch
modes and the controller causes the regulator to change from a
first conversion mode of the regulator to a second conversion mode
of the regulator, wherein the first conversion mode of the
regulator has a different conversion factor that the second
conversion mode of the regulator.
[0022] In some of these embodiments, the first output of the
controller is wirelessly coupled to the wireless charging
transmitter.
[0023] In some of these embodiments, the first output of the
controller is wirelessly coupled to the wireless charging
transmitter using the wireless charging receiver.
[0024] In some of these embodiments, the input of the regulator is
also coupled to an adapter port configured to be coupled to a wired
charging adapter.
[0025] In some of these embodiments, the input of the regulator is
also coupled to an adapter port configured to be coupled to a wired
charging adapter, the controller determines whether a wired
charging adapter is coupled to the adapter port, and when the
controller determines that a wired charging adapter is coupled to
the adapter port, the controller controls an output voltage
provided by the adapter.
[0026] In some of these embodiments, the input of the regulator is
also coupled to an adapter port configured to be coupled to a wired
charging adapter and the controller controls the output voltage
provided by the adapter to be an integer multiple of a voltage
provided at the output of the regulator.
[0027] In some of these embodiments, the input of the regulator is
also coupled to an adapter port configured to be coupled to a wired
charging adapter and the input of the regulator is coupled to the
wireless charging receiver by a switch.
[0028] In some of these embodiments, the input of the regulator is
also coupled to an adapter port configured to be coupled to a wired
charging adapter and the input of the regulator is coupled to the
adapter port by a switch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Various objects, features, and advantages of the disclosed
subject matter can be more fully appreciated with reference to the
following detailed description of the disclosed subject matter when
considered in connection with the following drawings, in which like
reference numerals identify like elements.
[0030] FIG. 1 depicts an example of a block diagram of a typical
charging system for a mobile device as known in the prior art.
[0031] FIG. 2 illustrates an example of a flow diagram showing an
example of a process that can be used to operate a voltage
regulator system in accordance with some embodiments.
[0032] FIGS. 3A-3B illustrate examples of graphs showing the
operation of a voltage regulator system in accordance with some
embodiments.
[0033] FIGS. 4A-4B illustrate examples of graphs showing the
operation of a voltage regulator system with non-idealities in
accordance with some embodiments.
[0034] FIG. 5 illustrates an example of a graph showing the
efficiency curves of a switched capacitor (SC) regulator with
non-idealities in accordance with some embodiments.
[0035] FIG. 6 illustrates an example of a graph showing efficiency
curves of a reconfigurable SC regulator at two conversion modes in
accordance with some embodiments.
[0036] FIG. 7 illustrates an example of a graph showing efficiency
curves of a hybrid regulator at three conversion modes in
accordance with some embodiments.
[0037] FIG. 8 shows an example of a flow diagram illustrating an
example of a process that can be used to operate a voltage
regulator system having a reconfigurable SC regulator or a hybrid
regulator in accordance with some embodiments.
[0038] FIG. 9 shows an example of a detailed flow diagram
illustrating an example of a process that can be used to operate a
controller in the voltage regulator system in accordance with some
embodiments.
[0039] FIG. 10 shows an example of a block diagram of a charging
system of a mobile device in accordance with some embodiments.
[0040] FIG. 11 depicts an example of a block diagram of a typical
wireless charging system for a mobile device as known in the prior
art.
[0041] FIG. 12 depicts an example of a block diagram of a wireless
charging system for a mobile device in accordance with some
embodiments.
[0042] FIG. 13 depicts an example of a block diagram of a wireless
charging system for a mobile device that can also be connected to a
wired charging adapter in accordance with some embodiments.
DETAILED DESCRIPTION
[0043] In the following description, numerous specific details are
set forth regarding examples of apparatuses, systems, and methods
that can be implemented in accordance with the disclosed subject
matter and the environment in which such apparatuses, systems, and
methods may operate, in order to provide a thorough understanding
of the disclosed subject matter. It will be apparent to one skilled
in the art, however, that the disclosed subject matter may be
practiced without such specific details, and that certain features,
which are well known in the art, are not described in detail in
order to avoid over complicating the disclosed subject matter. In
addition, it will be understood that the examples provided below
are for illustration purposes, and that it is contemplated that
there are other apparatuses, systems, and methods that are within
the scope of the disclosed subject matter that differ from the
examples provided.
[0044] Fast battery charging is an important feature of mobile
devices. FIG. 1 depicts an example of a typical charging system of
a mobile device. The charging system includes a mobile device 102,
which includes, among other things, a regulator 104 and a battery
106. Regulator 104 is configured to provide power to battery 106 so
that the battery is charged using the power provided by regulator
104.
[0045] Regulator 104 in mobile device 102 is configured to couple
to an adapter 108. Adapter 108 is configured to receive a high AC
input voltage (e.g., 110-220V) V.sub.OUT.sub._.sub.WALL from a
power outlet 110 and convert V.sub.OUT.sub._.sub.WALL to a lower DC
voltage V.sub.BUS. Adapter 108 then provides the DC voltage
V.sub.BUS to voltage regulator 104 through an interface, such as a
USB port. Adapter 108 typically includes an AC/DC converter
followed by a DC/DC converter.
[0046] Regulator 104 is configured to receive V.sub.BUS from
adapter 108 and provide an output voltage V.sub.BAT. The output
voltage V.sub.BAT (and the corresponding current I.sub.CHG) is then
routed to battery 106 to charge the battery. Regulator 104
typically includes a DC/DC converter, and more specifically, a
switching-inductor voltage regulator, such as a buck regulator.
[0047] In order to increase the charging speed of the battery,
regulator 104 needs to deliver a higher amount of power to battery
106. Since the amount of power delivered by regulator 104 is
computed as the multiplication of the output voltage V.sub.BAT and
the corresponding current I.sub.CHG, regulator 104 should increase
either the output current I.sub.CHG or the output voltage V.sub.BAT
in order to increase the charging speed.
[0048] Typically, regulator 104 cannot control the output voltage
V.sub.BAT. The output voltage V.sub.BAT is typically determined by
the battery, and in particular, the battery chemistry (e.g.,
Li-Ion), number of battery cells stacked, and the amount of charge
that had been accumulated in the battery, also referred to as a
charge state. For example, the output voltage V.sub.BAT, which is
equivalent to the voltage across the battery, is increased as the
battery becomes more charged. A single stack Li-Ion battery
typically has a battery voltage V.sub.BAT of 3-4.5V. Typically, the
battery voltage is 3V when the battery is completely discharged,
and the battery voltage is 4.5V when the battery is completely
charged. The battery voltage can gradually increase from 3V to 4.5V
as the battery is charged from 0% to 100%. Therefore, regulator 104
cannot control the output voltage V.sub.BAT. Hence, in order to
increase the power delivered to battery 106, regulator 104
generally has to increase the output current I.sub.CHG.
[0049] In order for regulator 104 to deliver an increased amount of
power (e.g., an increased amount of current I.sub.CHG) to battery
106, regulator 104 should receive an increased amount of power from
adapter 108. This means that, in order to deliver an increased
amount of power to battery 106, adapter 108 should also increase
the output current I.sub.BUS and/or the output voltage V.sub.BUS
provided to regulator 104.
[0050] It is often challenging for adapter 108 to increase the
amount of output current I.sub.BUS because interface protocols for
connecting adapter 108 to regulator 104 typically limit the amount
of current that can flow through the interface compliant with the
interface protocols. For example, USB standards limit the amount of
current flowing through a USB Type C interface to 3 A. Moreover,
for the adapter cable to withstand a large amount of current, the
adapter cable should be made thicker, which, in turn, increases the
cost of manufacturing the adapter cable. In fact, adapter cables
actually became more expensive as the adapter cables were designed
to accommodate higher current.
[0051] Instead of increasing the output current I.sub.BUS, adapter
108 could increase the output voltage V.sub.BUS to deliver an
increased amount of power. However, such a strategy is not ideal
when regulator 104 uses a buck regulator. If the output voltage
V.sub.BUS is increased, regulator 104 needs to operate at a higher
voltage conversion ratio to convert a large V.sub.BUS to V.sub.BAT.
Unfortunately, operating regulator 104 at a high voltage conversion
ratio is problematic when regulator 104 uses a buck regulator
because the efficiency of a buck regulator degrades as the
conversion ratio (e.g., V.sub.BUS/V.sub.BAT) increases.
[0052] The reduced efficiency of a regulator such as regulator 104
is highly problematic because it increases power dissipation. For
example, the efficiency of a regulator can be written as
follows:
Efficiency=P.sub.OUT/P.sub.IN=(P.sub.IN-P.sub.DISS)/P.sub.IN
where P.sub.IN is the input power, P.sub.OUT is the output power,
and P.sub.DISS is the power dissipated by the regulator. Based on
this relationship, the amount of power dissipated by the regulator
can be derived as follows:
P.sub.IN*Efficiency=P.sub.IN-P.sub.DISS
P.sub.DISS=P.sub.IN*(1-Efficiency)
When V.sub.BUS (the input voltage to the regulator) increases, the
following two factors cause P.sub.DISS to increase as well: (1)
P.sub.IN increases with a higher input voltage, which is V.sub.BUS;
and (2) the efficiency decreases with a higher conversion
ratio.
[0053] The increased power dissipation (P.sub.DISS) is a big
problem for mobile devices because increased power dissipation
leads to increased heat dissipation. There are strong restrictions
on how hot a surface of a mobile device can be to protect users.
Because mobile devices generally do not include a cooling
mechanism, the heat dissipation budget is very tight. As a result,
when a regulator dissipates too much heat, the regulator is
typically designed to throttle the battery charging speed in order
to reduce heat dissipation. This is undesirable for user
experience.
[0054] Therefore, in order to maintain high speed charging under a
tight heat dissipation budget, there is a strong need to provide a
charging system that is capable of maintaining a high efficiency at
high input-to-output conversion ratios.
[0055] Some embodiments of the disclosed subject matter include a
voltage regulator system embedded in a mobile device to accommodate
high speed charging of the mobile device. The voltage regulator
system is capable of regulating the operation of a voltage
regulator to maintain a high efficiency at high input-to-output
conversion ratios.
[0056] FIG. 10 shows a charging system of a mobile device in
accordance with some embodiments. The charging system includes a
mobile device 102 that has a battery 106, an adapter 108, and a
power outlet 110, similarly to the charging system disclosed in
FIG. 1. However, the charging system also includes a voltage
regulator system 1002, which in turn includes a controller 1004 and
a regulator 1006. Regulator 1006 includes an input terminal and an
output terminal. The input terminal of the regulator is coupled to
adaptor 108 to receive an input voltage, and the output terminal of
the regulator is coupled to battery 104 to provide an output
voltage to battery 104 for charging. Controller 1004 is configured
to regulate the operation of regulator 1006 to maintain a high
efficiency at high input-to-output conversion ratios.
[0057] In some embodiments, regulator 1006 includes a
switched-capacitor (SC) regulator (also referred to as an SC
converter). An SC regulator can use one or more capacitors to
transfer charge from an input terminal (e.g., which is connected to
a power source) to an output terminal (e.g., which is connected to
an output load). An SC regulator can use power switches to rapidly
connect/disconnect one or more capacitors to/from multiple voltage
levels (each at a different point in time), thereby providing an
output voltage that is a weighted average of the multiple voltage
levels. The SC regulator can control the output voltage by changing
the configuration, the sequence, and the duty cycle in which
capacitors are coupled to one another.
[0058] Hereinafter, the term conversion ratio refers to the actual
voltage ratio between the input voltage and the output voltage of a
regulator, and the term conversion mode refers to a voltage ratio
(e.g., a conversion factor) between the input voltage and the
output voltage at which an ideal regulator (without non-idealities)
achieves the highest efficiency. For example, an ideal SC regulator
operating at a conversion mode of 2:1 achieves the highest
efficiency when the conversion ratio of the SC regulator is 2, but
the SC regulator operating at a conversion mode of 2:1 can still
operate at a conversion ratio of 2.5, albeit at a lower efficiency.
In an ideal SC regulator, the conversion ratio can be equal to the
conversion factor of the conversion mode, but in a non-ideal SC
regulator, the conversion ratio is generally larger than the
conversion factor of the conversion mode.
[0059] While buck regulators have poor efficiencies at high
conversion ratios, SC regulators tend to have a high efficiency
even when the conversion ratio is high. In particular, SC
regulators tend to have a high efficiency when the conversion ratio
is close to an integer number, regardless of the actual value of
the conversion ratio. Unfortunately, the efficiency of an SC
regulator degrades as the conversion ratio deviates from an integer
number. For example, an SC regulator can achieve high efficiencies
when the input voltage is N times the output voltage of the SC
regulator. However, the same SC regulator may not provide high
efficiencies when the output voltage deviates from N.
[0060] In some embodiments, in order to maintain a high efficiency
of the SC regulator in regulator 1006, controller 1004 can be
configured to maintain a conversion ratio of the SC regulator close
to an integer number. When the input-to-output voltage conversion
ratio of the SC regulator deviates from an integer value--in part
due to the increase of the battery voltage as the battery is
charged-controller 1004 can request that the adapter increase the
input voltage to the SC regulator so that the input-to-output
voltage conversion ratio remains close to an integer value.
[0061] For example, suppose the SC regulator in regulator 1006 is
operating at a conversion mode having a conversion factor of 2, and
the output voltage of regulator 1006 (e.g., V.sub.BAT) keeps rising
as the battery is charged (e.g., from 3V to 4.5V in single stack
Li-Ion batteries). In that case, controller 1004 can send an
instruction (e.g., a signal) to adapter 108, requesting that the
adapter increase its output voltage (e.g., V.sub.BUS) so that the
output voltage is close to 2.times.V.sub.BAT. That way, the
conversion ratio of SC regulator 1006 can be maintained close to
the conversion factor of the conversion mode.
[0062] Because the battery voltage (V.sub.BAT) changes quite slowly
and predictably (e.g., determined by the battery chemistry, number
of battery cells stacked, and the charge state of the battery), it
is possible for adapter 108 to reliably provide its output voltage
(e.g., V.sub.BUS) that is N times greater than the battery voltage
(V.sub.BAT).
[0063] FIG. 2 illustrates an example of a flow diagram showing an
example 200 of a process that can be used to operate a voltage
regulator system, such as voltage regulator system 1002 shown in
FIG. 10, in accordance with some embodiments. In block 202, a
controller is configured to determine a conversion ratio of a SC
regulator in the voltage regulator system. In block 204, the
controller is configured to determine a difference between the
conversion ratio of the SC regulator and the conversion factor of
the conversion mode of the SC regulator. If that difference is
greater than a predetermined threshold value, the controller is
configured to send a request to an adapter to change the input
voltage to the SC regulator so that the conversion ratio becomes
closer to the conversion factor of the conversion mode. For
example, when the conversion ratio is greater than the conversion
factor of the conversion mode by more than the predetermined
threshold, the controller can request that the adapter decrease the
input voltage to the SC regulator; when the conversion ratio is
greater than the conversion factor of the conversion mode by less
than the predetermined threshold, the controller can request that
the adapter increase the input voltage to the SC regulator. In some
embodiments, the predetermined threshold can be zero.
[0064] In some embodiments, in block 204, the controller is
configured to send a request to the adapter to increase the input
voltage (V.sub.BUS) to the SC regulator when the conversion ratio
is less than the conversion factor of the conversion mode. In some
cases, the controller is configured to send the request to the
adapter until the conversion ratio becomes greater than the
conversion mode. This way, the conversion ratio can be regulated to
be greater than the conversion factor of the conversion mode during
the operation of the regulator.
[0065] In some embodiments, the controller is configured to send
the request to the adapter via a data signal line coupled to the
adapter. For example, the controller can be configured to use the
D+ and D- pins on most adapters to send the request. In other
embodiments, the controller is configured to send the request to
the adapter by modulating the output voltage provided by the
adapter (V.sub.BUS). In other embodiments, when the adapter is a
USB Type C adapter, the controller is configured to send the
request to the adapter using CC1 and CC2 pins. In some embodiments,
the controller sends the request to the adapter in compliance with
one or more wire communication protocols. Such wire communication
protocols can include, for example, Qualcomm QuickCharge 2.0,
Qualcomm QuickCharge 3.0, Samsung Adaptive Fast Charging, MediaTek
Pump Express 2.0, MediaTek Pump Express 3.0, USB Power Delivery
2.0, USB Power Delivery 3.0, or any other suitable wire
communication protocols or combination of protocols.
[0066] In some embodiments, the process of FIG. 2 can be
implemented in voltage regulator 1004 using controller 1006 and
adapter 108, all illustrated in FIG. 10.
[0067] FIGS. 3A-3B illustrate examples of graphs showing the
operation of a voltage regulator system such as that shown in FIG.
10 in accordance with some embodiments. FIG. 3A shows an input
voltage of an SC regulator as a battery is charged; FIG. 3B shows
an interrupt signal indicating a time instance at which to increase
the input voltage of the SC regulator. The vertical axis of the
graphs show voltage levels, and the horizontal axis of the graphs
shows time. These graphs illustrate the operation of an embodiment
of a voltage regulator system in which (1) the SC regulator is
operating at a conversion mode of N:1 (the conversion factor of
N:1), and (2) the controller is configured to request that an
adapter change the input voltage to the SC regulator when the
conversion ratio of the SC regulator is less than the conversion
mode of the SC regulator (e.g., when V.sub.BUS is less than
N.times.V.sub.BAT). When the battery is discharged, the battery
voltage V.sub.BAT is equal to V.sub.BAT.sub._.sub.MIN. As the
battery gets charged by the voltage regulator system, the battery
voltage V.sub.BAT increases to V.sub.BAT.sub._.sub.MAX, shown as a
dotted line N.times.V.sub.BAT 302 in FIG. 3A.
[0068] As the battery gets charged and the battery voltage
V.sub.BAT increases from V.sub.BAT.sub._.sub.MIN to
V.sub.BAT.sub._.sub.MAX, the battery voltage V.sub.BAT may become
sufficiently large such that N.times.V.sub.BAT 302 becomes greater
than the input voltage V.sub.BUS. This indicates that the
conversion ratio is less than the conversion mode. In this case,
the controller is configured to request the adaptor to increase
V.sub.BUS 304 so that V.sub.BUS 304 remains higher than
N.times.V.sub.BAT 302. This request can be a single bit interrupt
signal V.sub.IN.sub._.sub.INC.sub._.sub.INT as shown in FIG. 3B.
The controller can trigger the single bit signal
V.sub.IN.sub._.sub.INC.sub._.sub.INT 306 when N.times.V.sub.BAT 302
becomes greater than the input voltage V.sub.BUS 304. The
controller can repeat this process until the battery is charged up
to a certain percentage or fully charged. In some embodiments, the
adaptor can be configured to increase the input voltage V.sub.BUS
304 to the SC regulator in steps: a voltage step
V.sub.BUS.sub._.sub.MIN.sub._.sub.STEP 308 at a time. In this case,
the input voltage V.sub.BUS 304 provided to the SC regulator would
look like a staircase, as shown in FIG. 3A. In some embodiments,
V.sub.BUS.sub._.sub.MIN.sub._.sub.STEP 308 can be a voltage between
1 mV and 2V, or any other suitable voltage range.
[0069] In reality, an SC regulator typically cannot precisely
convert N.times.V.sub.BAT to V.sub.BAT because of non-idealities
such as, for example, voltage drops caused by a parasitic
resistance. Instead, a typical SC regulator would convert an input
voltage N.times.V.sub.BAT to an output voltage that is lower than
V.sub.BAT. The non-idealities can be modeled as a voltage
margin.
[0070] FIGS. 4A-4B illustrate examples of graphs showing the
operation of a voltage regulator system such as that shown in FIG.
10 with non-idealities in accordance with some embodiments. When
the non-idealities are taken into account, the controller can
effectively request the adapter to increase V.sub.BUS 304 when
N.times.V.sub.BAT 302+V.sub.MAR 402 becomes greater than the input
voltage V.sub.BUS. In some embodiments, V.sub.MAR 402 can be a
voltage between 1 mV and 2V, or any other suitable voltage
range.
[0071] FIG. 5 illustrates an example of a graph of the efficiency
of an SC regulator with non-idealities in accordance with some
embodiments. Starting from the right side of the plot, the
efficiency of the SC regulator, shown by efficiency curve 502,
increases as the conversion ratio (V.sub.BUS/V.sub.BAT) approaches
the conversion mode N. The efficiency curve reaches a peak value
(at operating point A 504) at some point, and starts to drop
rapidly like a "cliff" as the conversion ratio gets closer to the
conversion mode N. In other words, as V.sub.SC.sub._.sub.DROP,
which is equal to V.sub.BUS/N-V.sub.BAT, approaches 0, the
efficiency 502 of the SC regulator drops rapidly. An N:1 SC
regulator cannot regulate V.sub.BAT to V.sub.BUS/N in non-ideal
conditions because V.sub.SC.sub._.sub.DROP cannot be equal to
0.
[0072] As shown by efficiency curve 506, efficiency curve 502
shifts to the right as the parasitic voltage drop increases, which
can be caused by higher output current. Even when V.sub.BUS and
V.sub.BAT are fixed, efficiency curve 502 can shift to the right
when output current changes. Because the efficiency curve depends
on the output current, it is difficult to predetermine an operating
point (e.g., the conversion ratio) of an SC regulator without
sacrificing the efficiency of the SC regulator. For example, when
the parasitic voltage drop is small, operating point A 504 on
efficiency curve 502 is the most efficient operating point for an
SC regulator. Therefore, the SC regulator can be operated at an
operating point A 504 to maximize the SC regulator efficiency.
However, if the parasitic voltage drop is large, efficiency curve
502 shifts to the right, and the same conversion ratio for that SC
regulator now has a very low efficiency, as shown by operating
point B 508. Such a low efficiency could cause heat problems due to
excessive power dissipation and could cause the voltage regulator
system to lose output regulation and therefore not be able to
regulate the output voltage to a desired value.
[0073] In some embodiments, a voltage regulator system, such as
voltage regulator system 1002 shown in FIG. 10, can be configured
to operate an SC regulator at a sub-optimal operating point that is
away from peak operating point 504. For example, such a voltage
regulator system can be configured to operate an SC regulator at an
operating point C 510 that has a conversion ratio sufficiently
offset from the conversion ratio corresponding to peak operating
point A 504. The offset between the conversion ratio of operating
point C 510 and the conversion ratio of peak operating point A 504
provides a safety margin that protects the SC regulator from
entering into a low efficiency mode.
[0074] In some embodiments, once a voltage regulator system, such
as voltage regulator system 1002 shown in FIG. 10, determines the
operating point for its SC regulator, the voltage regulator system
can request that an adapter provide V.sub.BUS so that the
conversion ratio of the SC regulator is matched to the conversion
ratio associated with the determined operating point.
[0075] In some embodiments, a regulator used in such a voltage
system can be a reconfigurable SC regulator that can be
reconfigured to operate in one of a plurality of conversion modes,
each associated with one of a plurality of integer conversion
ratios. For example, a 3:1 reconfigurable SC regulator can support
three conversion modes: 3:1, 2:1, and 1:1.
[0076] In some embodiments, a controller can be used to reconfigure
the conversion mode of the reconfigurable SC regulator based on the
conversion ratio of the reconfigurable SC regulator. For example,
when the conversion ratio is close to 3:1, a controller can
configure the reconfigurable SC regulator to operate in the 3:1
conversion mode. As the conversion ratio decreases (e.g., because
the input voltage decreases or the output voltage increases), the
controller can configure the reconfigurable SC regulator to operate
in the 2:1 conversion mode. As the conversion ratio decreases
further to a point where the conversion ratio is close to 1:1, the
controller can configure the reconfigurable SC regulator to operate
in the 1:1 conversion mode. This allows the voltage regulator
system to accommodate a wide range of input voltages without a
significant loss of efficiency.
[0077] In some embodiments, a regulator used in a voltage regulator
system can include a reconfigurable SC regulator as disclosed in
U.S. patent application Ser. No. 15/092,037, titled "ASYMMETRIC
SWITCHING CAPACITOR REGULATOR," filed on Apr. 6, 2016, by Crossley
et al.; and/or U.S. Provisional Patent Application No. 62/324,091,
titled "RECONFIGURABLE DICKSON STAR SWITCHED CAPACITOR VOLTAGE
REGULATOR," filed on Apr. 18, 2016, by Puggelli et al., each of
which is hereby incorporated by reference herein in its
entirety.
[0078] In embodiments in which a regulator such as regulator 1006
of FIG. 10 includes a reconfigurable SC regulator, a controller can
be used to dynamically reconfigure the conversion mode of the
reconfigurable SC regulator based on a desired battery charging
speed. For example, suppose that a reconfigurable SC regulator is
operating at a conversion mode associated with a 2:1 conversion
ratio and it becomes desirable to charge a battery at a faster
speed. In this case, a controller can cause the reconfigurable SC
regulator to change the conversion mode so that the SC regulator
operates at a higher conversion mode N:1 (e.g., 3:1 or 4:1). Also,
the controller can request that an adapter increase the input
voltage of the reconfigurable SC regulator so that the input
voltage of the reconfigurable SC regulator is N times greater than
the battery voltage (V.sub.BAT). This allows the voltage regulator
system to dynamically vary the charging speed of the battery.
Voltage regulator system 1002 shown in FIG. 10 enables backwards
compatibility for fast charging, meaning that mobile devices
configured to be used with old charging cables that do not support
high current can also benefit from fast charging by increasing
V.sub.BUS 103 instead of I.sub.BUS 119.
[0079] In some embodiments, a controller, such as controller 1004
of FIG. 10, can reconfigure a reconfigurable SC regulator when the
controller detects that the efficiency of the reconfigurable SC
regulator at the current conversion mode is low. For example, when
the reconfigurable SC regulator efficiency is significantly reduced
due, in part, to an increased parasitic voltage drop, the
controller can reconfigure the reconfigurable SC regulator to
operate at a lower conversion mode. That way, the controller can
protect against a severe drop in efficiency of the reconfigurable
SC regulator.
[0080] FIG. 6 illustrates an example of graphs showing efficiency
curves of a reconfigurable SC regulator at two conversion
modes--N:1 and (N+1):1--in accordance with some embodiments. Curves
602, 604 show the efficiency of the reconfigurable SC regulator at
a conversion mode of N:1; and curves 606, 608 show the efficiency
of the reconfigurable SC regulator at a conversion mode of
(N+1):1.
[0081] Initially, the reconfigurable SC regulator can operate in
the conversion mode of (N+1):1 in which the parasitic voltage drop
is small (e.g., the output current is small). In this case, the
voltage regulator system including the reconfigurable SC regulator
can operate the reconfigurable SC regulator at optimal operating
point A 610. When the parasitic voltage drop becomes large (e.g.,
due to a larger output current), efficiency curve 606 would shift
to the right as shown by efficiency curve 608. Due to this increase
in the parasitic voltage drop, the efficiency of the reconfigurable
SC regulator would drop significantly (off the "cliff" portion of
efficiency curve 608).
[0082] To address this efficiency reduction, once a controller of
the voltage regulation system detects that the parasitic voltage
drop has increased, the controller can reconfigure the
reconfigurable SC regulator to operate at a conversion mode of N:1,
instead of (N+1):1. This way, the reconfigurable SC regulator can
be forced to operate on efficiency curve 604, instead falling off
the "cliff" on efficiency curve 608. In other words, the voltage
regulator system can reconfigure the reconfigurable SC regulator so
that the reconfigurable SC regulator operates at an operating point
B 612. Since the controller can reconfigure the reconfigurable SC
regulator to protect against a severe drop in efficiency, the
controller can operate the reconfigurable SC regulator at its
optimal operating point A 610.
[0083] In some embodiments, once the controller determines the
operating point for the reconfigurable SC regulator, the controller
can request that an adapter provide V.sub.BUS so that the
conversion ratio of the reconfigurable SC regulator is matched to
the conversion ratio associated with the determined operating
point.
[0084] In some embodiments, a regulator, such as regulator 1006,
can include a hybrid regulator, also referred to as a two-stage
regulator. A hybrid regulator includes a series of two voltage
regulators: a first stage regulator and a second stage regulator.
In some embodiments, the first stage regulator includes an SC
regulator and the second stage regulator includes a switching
voltage regulator (e.g., buck regulator). Such a hybrid regulator
takes advantage of the fact that SC regulators are good at dividing
voltages across predetermined fractional values and that switching
voltage regulators can be good at regulating a wide range of output
voltage in fine steps. This allows the hybrid regulator to achieve
a high conversion efficiency even at non-integer conversion
ratios.
[0085] In some embodiments, such a hybrid regulator can include a
hybrid regulator as disclosed in U.S. Pat. No. 9,143,032, titled
"APPARATUS, SYSTEMS, AND METHODS FOR PROVIDING A HYBRID POWER
REGULATOR," issued on Sep. 22, 2015, to Lion Semiconductor Inc.;
and/or U.S. Provisional Patent Application No. 62/324,091, titled
"RECONFIGURABLE DICKSON STAR SWITCHED CAPACITOR VOLTAGE REGULATOR,"
filed on Apr. 18, 2016, by Puggelli et al., collectively the
"Hybrid Regulator Documents", each of which is hereby incorporated
by reference herein in its entirety.
[0086] In some embodiments, a hybrid regulator can support a
plurality of conversion modes to support different conversion
ratios. For example, a hybrid regulator with (1) a reconfigurable
3:1 SC regulator and (2) a switched-inductor regulator can support
five modes of operation: a S3 conversion mode, a H32 hybrid
conversion mode, a S2 conversion mode, a H21 hybrid conversion
mode, and a S1 conversion mode.
[0087] As discussed in the Hybrid Regulator Documents, a hybrid
regulator can dither between two or more conversion modes of a
reconfigurable SC regulator to provide an "average" output voltage
of the two or more conversion modes of a reconfigurable SC
regulator. For example, a hybrid regulator, operating in a H32
hybrid conversion mode, can receive an input voltage V.sub.IN and
dither between a 2:1 switched capacitor conversion mode, also
referred to as a S2 conversion mode, and a 3:1 switched capacitor
conversion mode, also referred to as a S3 conversion mode, to
provide an output voltage that is between V.sub.IN/2 and
V.sub.IN/3.
[0088] In some embodiments, the actual output voltage of a hybrid
regulator in a hybrid conversion mode (e.g., H32 hybrid conversion
mode) is determined by the proportion of time (e.g., duty cycle)
spent in each switched capacitor conversion mode. For example, when
the hybrid regulator spends D amount of time in a S2 conversion
mode and (1-D) amount of time in a S3 conversion mode, the output
voltage would be (D.times.V.sub.IN/2+(1-D).times.V.sub.IN/3).
Therefore, by controlling the value of the duty cycle D, the output
voltage of the hybrid regulator can be accurately controlled.
[0089] In some embodiments, a hybrid conversion mode can have a
conversion factor that is non-integer. For example, the H32 hybrid
conversion mode can have a conversion factor of (2D+3(1-D)). More
generally, the H(N+1)N hybrid conversion mode can have a conversion
factor of (D.times.N+(1-D).times.(N+1)).
[0090] In some embodiments, a controller, such as controller 1004
shown in FIG. 10, can configure a hybrid regulator with one of a
plurality of conversion modes supported by the hybrid regulator
based on the conversion ratio of the hybrid regulator. For example,
when the conversion ratio of the hybrid regulator is close to 3:1,
the hybrid regulator can operate in the S3 conversion mode. As the
conversion ratio decreases (e.g., because the input voltage
decreases or the output voltage increases), the controller can
configure the hybrid regulator to operate in the H32 conversion
mode. As the conversion ratio decreases further to a point where
the conversion ratio is close to 2:1, the controller can configure
the hybrid regulator to operate in the S2 conversion mode. As this
process continues, the hybrid regulator can in some embodiments be
configured to operate in the H21 conversion mode, and eventually in
the S1 conversion mode. The conversion mode transitions to a
"lower" mode as the hybrid regulator transitions from the S_N
conversion mode (a N:1 switching capacitor conversion mode) to the
S1 conversion mode; and the conversion mode transitions to a
"higher" mode as the hybrid regulator transitions from the S1
conversion mode to the S_N conversion mode.
[0091] In some embodiments, a voltage regulator system, such as
voltage regulator 1002 shown in FIG. 10, can improve its efficiency
across a large range of conversion ratios by using a hybrid
regulator. FIG. 7 illustrates an example of a graph showing
efficiency curves of a hybrid regulator at three conversion
modes--the switched capacitor N:1 mode, the switched capacitor
(N+1):1 mode, and the hybrid H(N+1)N mode--in accordance with some
embodiments. A controller in the voltage regulator system can
configure a hybrid regulator in the voltage regulator system to
operate at a particular conversion mode to improve the voltage
regulator system's efficiency across a large range of conversion
ratios. As discussed above, a hybrid regulator can dither between
two switched capacitor conversion modes. Efficiency curves that can
be associated with two such switched capacitor conversion modes are
shown by curves 702 and 704. The dithering between the switched
capacitor conversion modes in effect replaces the "cliff" in the
efficiency curve 704 with a line 706 that connects the efficiency
curves 702 and 704. Therefore, the hybrid regulator does not have a
risk of a sudden degradation of efficiency and a loss of output
regulation even when there is a large fluctuation in the parasitic
voltage drop. For example, when the hybrid regulator is in the
(N+1):1 switched capacitor conversion mode and is about to lose the
output regulation and drop off the "cliff," the controller can
configure the hybrid regulator to operate to the H(N+1)N hybrid
conversion mode. This allows the voltage regulator system to
operate at a high efficiency operating point across a large range
of conversion ratios.
[0092] FIG. 8 shows an example of a flow diagram illustrating an
example of a process that can be used to operate a voltage
regulator system, such as voltage regulator system 1002 shown in
FIG. 10, having a reconfigurable SC regulator or a hybrid regulator
in accordance with some embodiments. In block 802, a controller
receives an instruction to charge the battery at a particular
charging speed. In block 804, the controller is configured to
determine the conversion mode of the regulator that could
accommodate the particular charging speed, and configure the
regulator to operate at that determined conversion mode.
[0093] In some embodiments, the controller is configured to
determine the initial conversion mode of the regulator using a
conversion mode table. The conversion mode table can include a
mapping between a target charging speed and a corresponding
conversion mode. Therefore, when the controller receives an
indication that the target charging speed should be at a first
level, the controller can determine the conversion mode associated
with that first level using the conversion mode table. In some
embodiments, the target charging speed is represented as the target
charging current I.sub.CHG. In such embodiments, the conversion
mode table can include a mapping between the target charging
current I.sub.CHG and the conversion mode.
[0094] In some embodiments, the controller is configured to
determine the initial conversion mode based on a ratio between (1)
the target charging current and (2) the maximum output current of
an adapter that provides power to the regulator. For example, when
the target charge current I.sub.CHG is 5 A and the maximum output
current of the adapter (I.sub.BUS.sub._.sub.MAX) is 3 A, the
controller can determine a ratio between the target charge current
I.sub.CHG and the maximum output current of the adapter,
I.sub.BUS.sub._.sub.MAX, to determine that the target conversion
ratio is close to 5/3. Therefore, the controller is configured to
set the conversion mode of the regulator to be at the S2 conversion
mode or the H21 conversion mode. As another example, when the
target charge current I.sub.CHG is 8 A and the maximum output
current (I.sub.BUS.sub._.sub.MAX) of an adapter providing power to
the regulator is 3 A, the controller can determine a ratio between
the target charge current I.sub.CHG and the maximum output current
of the adapter, I.sub.BUS.sub._.sub.MAX, to determine that the
target conversion ratio is close to 8/3. Therefore, the controller
is configured to set the conversion mode of the regulator to be at
the S3 conversion mode or the H32 conversion mode.
[0095] Once the controller determines the initial conversion mode
and configures the regulator to operate in the initial conversion
mode, the controller can track the efficiency of the regulator to
determine, in substantially real-time, the conversion mode that is
most energy-efficient, as discussed in blocks 806-808.
[0096] In block 806, the controller is configured to determine a
conversion ratio of the regulator (e.g., the present value of
V.sub.BUS/V.sub.BAT). In block 808, the controller is configured to
compare the determined conversion ratio with the conversion mode of
the regulator. If the difference between the conversion ratio and
the conversion mode of regulator is greater than a threshold value,
then the controller is configured to send a request to the adapter
to change the input voltage V.sub.BUS to the regulator. In some
embodiments, in block 808, the controller is configured to send the
request to the adapter when the input voltage V.sub.BUS is less
than (conversion factor).times.V.sub.BAT. The controller can
iterate blocks 806 and 808 to maintain a conversion ratio that is
close to the conversion factor associated with the conversion mode
in which the regulator operates.
[0097] In some embodiments, the iteration of blocks 806 and 808 can
be interrupted when the controller receives a newly desired battery
charging speed, in which case process 800 will loop back to block
802 (which looping back is not shown in FIG. 8). In some
embodiments, the iteration of the blocks 806 and 808 can be
interrupted when the controller determines that the efficiency of
the regulator is low. In this case, the controller is configured to
loop back to block 804 to determine a better conversion mode for
the regulator (which looping back is not shown in FIG. 8).
[0098] In some embodiments, the efficiency of the regulator can be
measured by measuring the input power and output power of the
regulator. The input power and the output power can be measured
using circuits such as analog to digital converters (ADCs). For
example, one or more ADCs can measure the input voltage and the
input current to determine the input power, and one or more ADCs
can measure the output voltage and output current to determine the
output power. In some cases, a single ADC can measure both the
input power and the output power.
[0099] FIG. 9 shows an example of a detailed flow diagram
illustrating an example 900 of a process that can be used to
operate a controller in the voltage regulator system, such as
voltage regulatory system 1002 shown in FIG. 10, in accordance with
some embodiments.
[0100] At a high level, in process 900, the controller operates in
four phases: an enable phase 902, an initial-operating-point-setup
phase 904, a decrement-loop phase 906, and an increment-loop phase
908.
[0101] During enable phase 902, the controller is configured to
enable the regulator in the voltage regulator system.
[0102] During initial-operating-point-setup phase 904, the
controller is configured to determine the initial conversion mode
for the regulator. For example, if the regulator in the voltage
regulator system is a hybrid regulator, the hybrid regulator can be
configured to be in the H21 hybrid conversion mode; if the
regulator in the voltage regulator system is a reconfigurable SC
regulator, the reconfigurable SC regulator can be configured to be
in the S1 conversion mode. Subsequently, the controller sends one
or more requests to an adapter that provides power to the voltage
regulator system to increase the input voltage (V.sub.BUS) to the
regulator so that the input voltage V.sub.BUS is substantially
close to (conversion factor).times.(output voltage of the regulator
(V.sub.BAT)).
[0103] During decrement-loop-phase 906 and increment-loop phase
908, once the regulator is in the target conversion mode and the
input voltage V.sub.BUS is substantially close to (conversion
factor).times.(output voltage of the regulator (V.sub.BAT)), the
voltage regulator system is configured to adjust the adapter output
(the input voltage V.sub.BUS) so that the regulator can stay in
that conversion mode. For example, if the regulator's conversion
ratio is higher than the conversion factor associated with the
conversion mode (e.g., meaning V.sub.BUS/V.sub.BAT is larger than
the conversion factor of the conversion mode or V.sub.SCDROP is
larger than expected), the controller is configured to request that
the adapter decrease its output (the input voltage V.sub.BUS) so
that the conversion ratio of the regulator returns to the target
conversion factor of the conversion mode. Also, as another example,
if the regulator's conversion ratio is lower than the conversion
factor associated with the conversion mode (e.g., meaning
V.sub.BUS/V.sub.BAT is smaller than the conversion factor of the
conversion mode or V.sub.SCDROP is smaller than expected), the
controller is configured to request that the adapter increase its
output (the input voltage V.sub.BUS) so that the conversion ratio
of the regulator returns to the target conversion factor of the
conversion mode.
[0104] FIG. 9 illustrates the detailed operation of the four phases
in accordance with some embodiments. This figure illustrates an
embodiment in which a regulator reaches maximum efficiency at the
S2 conversion mode (e.g., at the conversion factor of 2).
Therefore, a controller is configured to adjust an adapter output
voltage (V.sub.BUS) so that the regulator stays at the S2
conversion mode as long as possible across the charge cycle.
[0105] During enable phase 902, in block 910, a mobile device is
coupled to the adapter. Once the mobile device is coupled to the
adapter, the controller is configured to perform an initialization
routine at block 912.
[0106] In some embodiments, the initialization routine includes
identifying the characteristics of the adapter. Identifying the
characteristics of the adapter can include, for example,
identifying whether the adapter is capable of adjusting its output
voltage (V.sub.BUS) upon receiving a request from the controller.
Identifying the characteristics of the adapter can also include,
for example, confirming that the adapter is compliant with a
particular standard (e.g., universal serial bus, or USB).
[0107] In some embodiments, the initialization routine can also
include requesting that the adapter provide a particular default
value as an output voltage (V.sub.BUS). For example, if the adapter
is USB-compliant, the controller can request that the adapter
provide 5 VDC as the default output value.
[0108] In some embodiments, the initialization routine can also
include setting a limit on the input current of the regulator so
that the regulator does not attempt to draw more current than what
the adapter can provide.
[0109] In some embodiments, the initialization routine can also
include confirming that the regulator is in the right conversion
mode for the desired conversion ratio.
[0110] In some embodiments, the adapter can be configured to
provide an output voltage (V.sub.BUS) of 5 VDC as the default
value. Because, the battery voltage (V.sub.BAT) for a battery
(e.g., a single-stack Li-Ion battery) is often between 3V and 4.5V,
the conversion ratio (V.sub.BUS/V.sub.BAT) of the regulator would
thus be generally between 1 and 2 in the initial mode. Therefore,
in the initial mode, if the regulator is a hybrid regulator, the
controller can be configured to set the conversion mode of the
regulator as H21 hybrid conversion mode. If the regulator is a
reconfigurable SC regulator that does not accommodate a hybrid
conversion mode, the controller can be configured to set the
conversion mode of the regulator as a S1 conversion mode.
[0111] Once the controller completes enable phase 902, the
controller moves to initial-operating-point-setup phase 904. In
this phase, the controller is configured to set the initial
operating point for the regulator.
[0112] In block 914, the controller is configured to check whether
there is a mode change by checking whether an interrupt signal,
named MODE_CHANGE_INT, has been asserted. When MODE_CHANGE_INT is
not asserted, the controller knows that the regulator is in the
initial operating mode (e.g., the H21 conversion mode for a hybrid
regulator, or the S1 conversion mode for a reconfigurable SC
regulator).
[0113] When MODE_CHANGE_INT is not asserted, the controller moves
to block 916. In block 916, since the controller is designed to
increase the adapter output voltage (V.sub.BUS) for faster battery
charging, the controller is configured to request that the adapter
increase its output voltage. In some embodiments, the controller
can be configured to request that the adapter increase its output
voltage by a particular voltage step (e.g.,
V.sub.MIN.sub._.sub.STEP).
[0114] In response to receiving the request from the controller,
the adapter can increase its output voltage (V.sub.BUS). When the
adapter increases its output voltage, the output voltage may have
some transient ripples or glitches. Therefore, after sending the
request to the adapter to increase the output voltage, the
controller can wait a predetermined period of time (so that the
ripples or glitches disappear) before moving onto the next block.
In some embodiments, the controller can repeat blocks 914 and 916
until there is a mode change (e.g., until the interrupt signal
MODE_CHANGE_INT is asserted).
[0115] When MODE_CHANGE_INT is asserted, the controller is
configured to update the conversion mode of the regulator to the
conversion mode that is one step higher than the prior conversion
mode. For example, if the regulator is a hybrid regulator, the
controller can update the conversion mode of the regulator from the
H21 conversion mode to the S2 conversion mode; if the regulator is
a reconfigurable SC regulator, the controller can update the
conversion mode of the regulator from the S1 conversion mode to the
S2 conversion mode.
[0116] In block 918 of decrement-loop phase 906, the controller is
configured to determine the current conversion mode of the
regulator. For example, the controller can check the signal
MODE_STS to determine the current conversion mode of the
regulator.
[0117] If the regulator is not in the S2 conversion mode (e.g., H32
or SC3) for some reason, in block 920, the controller is configured
to decrease the adapter output voltage by a voltage step (e.g.,
V.sub.BUS.sub._.sub.MIN.sub._.sub.STEP). The controller is
configured to decrease the adapter output voltage until the
regulator operates in the S2 conversion mode by repeating blocks
918 and 920.
[0118] If the regulator is in the S2 conversion mode (SC2), which
is what is expected, the regulator can operate as illustrated in
FIGS. 4A-4B, where the regulator increases the adapter output
voltage by a voltage step (e.g., V.sub.BUS MIN STEP) as the battery
is charged. The controller then moves to the increment-loop phase
908.
[0119] In block 922 of the increment-loop phase 908, the controller
is configured to enter into a sleep mode. This means that the
controller does not request that the adapter modify its output
voltage until the controller receives an interrupt signal or the
controller has been in the sleep mode for a predetermined period of
time.
[0120] In block 924, when the controller wakes up from the sleep
mode, the controller is configured to determine whether the
controller has received an interrupt signal (e.g., the interrupt
signal MODE_CHANGE_INT is asserted). If the controller has not
received the interrupt signal, in block 926, the controller is
configured to determine whether the adapter output voltage should
be increased. In some embodiments, the controller is configured to
determine whether the adapter output voltage (V.sub.BUS) should be
increased by analyzing another interrupt signal called
V.sub.IN.sub._.sub.INC.sub._.sub.INT, which can be generated by the
controller. In other embodiments, the controller is configured to
determine whether the adapter output voltage (V.sub.BUS) should be
increased by comparing the adapter output voltage and (conversion
factor).times.(battery voltage).
[0121] When the controller determines that the adapter output
voltage does not need to increase, then the controller returns to
the sleep mode in block 922. When the controller determines that
the adapter output voltage should increase, then in block 928, the
controller sends a request to the adapter to increase the output
voltage (V.sub.BUS) by a voltage step (e.g., V.sub.BUS MIN
STEP).
[0122] In block 930, the controller is configured to determine the
current conversion mode of the regulator by, for example, analyzing
the status signal MODE_STS. If the regulator 1006 is in the S2
conversion mode (SC2), the controller returns to the sleep mode in
block 922. If the regulator is in a lower mode such as the H21
conversion mode (H21) or the S1 conversion mode (SC1), the
controller is configured to request that the adapter increase the
output voltage by V.sub.BUS.sub._.sub.MIN.sub._.sub.STEP until the
regulator operates in the S2 conversion mode.
[0123] Going back to block 924, if the controller has received the
interrupt signal indicating that the conversion mode should change,
the controller is configured to determine the current conversion
mode by, for example, analyzing the status signal MODE_STS at block
912.
[0124] If the current conversion mode is lower than the S2
conversion mode, such as the H21 conversion mode or the S1
conversion mode, the controller performs block 928. If the current
conversion mode is higher than the S2 conversion mode, such as the
H32 conversion mode or the SC3 conversion mode, the controller may
perform one of two options. The first option is for the voltage
regulator system to stay in the current mode by moving to block 922
and wait for the battery voltage to increase to a point where the
voltage regulator system operates in the S2 conversion mode. The
second option is to go to block 920 of the decrement-loop phase 906
and decrease the adapter output voltage by
V.sub.BUS.sub._.sub.MIN.sub._.sub.STEP SO that the regulator can
enter into the S2 conversion mode more quickly.
[0125] While FIG. 9 illustrates an embodiment in which the
regulator reaches the maximum efficiency at the S2 conversion mode
(SC2) (e.g., at the conversion factor of 2), this operation can be
used in cases where the regulator reaches the maximum efficiency at
S_N conversion mode. In that case, S1, H21, H32, S3 can be changed
to S(N-1), H N(N-1), H_(N+1)N, S_(N+1) conversion modes,
respectively. In this case, the controller is configured to adjust
the adapter output voltage (V.sub.BUS) so that the regulator stays
at the S_N conversion mode as long as possible across the charge
cycle.
[0126] In some embodiments, when the regulator is a hybrid
regulator, the controller can be configured to adjust the adapter
output voltage so that the regulator stays in the switched
capacitor conversion mode (e.g., S2, S3, . . . S_N) as long as
possible, where N is an integer number larger than 1. Switched
capacitor conversion modes may be favorable to hybrid conversion
modes because the efficiency of the regulator at switched capacitor
conversion modes may be higher than the efficiency of the regulator
at hybrid conversion modes.
[0127] Turning to FIG. 11, an example of a typical wireless charger
system for charging a mobile device is shown. Like what is shown
in, and described in connection with, FIG. 1, the system of FIG. 11
includes a mobile device 102, a regulator 104, and a power outlet
110. However, unlike FIG. 1, the system of FIG. 11 includes a
wireless charging transmitter 1112 and a wireless charging receiver
1114. During operation, wireless charging transmitter 1112 wireless
transmits power to wireless charging receiver 1114. This wireless
transmission can be performed in any suitable manner, such as by
using an inductive coupling between the transmitter and the
receiver. The wireless transmission is illustrated in FIG. 11 by
line 1116.
[0128] FIG. 12 illustrates an example of a wireless charger system
for charging a mobile device in accordance with some embodiments.
Like what is shown in, and described in connection with FIG. 10,
the system of FIG. 11 includes a power outlet 110, a voltage
regulator system 1002, and a battery 106. Power outlet 110, voltage
regulator system 1002, and battery 106 can be implemented, and can
behave, similarly to what is described above. Unlike what is in
FIG. 10, the wireless charging system shown in FIG. 12 does not use
an adapter 108, but instead uses a wireless charging transmitter
1212 and a wireless charging receiver 1214.
[0129] In some embodiment, wireless charging transmitter 1212 can
include an inductor coil that is energized by the transmitter with
an AC voltage (having a given amplitude and a given frequency) so
as to produce a magnetic field (which is represented in FIG. 12 by
line 1216). In such embodiments, wireless charging receiver 1214
can include an inductor coil that is placed within this magnetic
field, resulting in power being received as a current that is
induced in the receiver's conductor coil by the magnetic field and
an AC voltage that is produced across the receiver's conductor
coil. To produce a V.sub.BUS output as a DC voltage, the receiver
can include a rectifier that converts the AC voltage on the
receiver's inductor coil to a DC voltage.
[0130] Like done by adapter 108 as described above, in some
embodiments, it may be desirable to adjust V.sub.BUS in order to
match a desired conversion ratio of regulator 1006 (e.g., when
regulator 1006 is a SC regulator). In some embodiments, in order to
do so, the amplitude and the frequency of the AC voltage used to
energize the inductor coil of the wireless charging transmitter can
be controlled so that the amplitude and the frequency of the AC
voltage on the inductor coil of the wireless charging receiver have
given values such that once the receiver's AC voltage is rectified,
the resulting DC voltage is a desired voltage V.sub.BUS.
[0131] In order to control the amplitude and the frequency of the
transmitter's AC voltage, controller 1004 can send one or more
wireless control signals to the wireless charging transmitter.
These wireless control signals can be transmitted using any
suitable mechanism. For example, these control signals can be
transmitted by the wireless charging receiver to the wireless
charging transmitter. More particularly, for example, the wireless
charging receiver can transmit control signals to the wireless
charging transmitter using backscatter modulation or any other
suitable wireless signal. Such backscatter modulation can operate
by the wireless charging receiver modulating the current drawn
through the inductor it uses to receive a charging signal from the
wireless charging transmitter, which modulates the current in the
inductor used by the wireless charging transmitter to transmit the
charging signal, and by the wireless charging transmitter
detecting, demodulating, and decoding the current modulation in its
inductor to produce a received control signal. Any suitable
information signals (i.e., signals that are not solely charging
signals) can be transmitted from the receiver to the transmitter in
this manner. In some embodiments, the wireless charging transmitter
can send one or more information signals to the wireless charging
receiver in similar manner by modulating the currents in the
transmitter's inductor so that the current in the receiver's
inductor is modulated, which can then be detected, demodulated, and
decoded to provide a received information signal at the
receiver.
[0132] In some embodiments, a wireless charging system can be
capable of both wired and wireless charging as shown in the example
of FIG. 13. As illustrated, a mobile device can have a voltage
regulator system 1002 that is coupled to both an adapter port 1302
and a wireless charging receiver 1214. Voltage regulator system
1002 can be coupled to both adapter port 1302 and wireless charging
receiver 1214 in any suitable manner, such as by one or more
switches, by a multiplexer, etc. In order to charge the mobile
device, a user can connect adapter port 1302 to an adapter 108,
which can receive power from a power outlet, not shown.
Alternatively, the user can place the mobile device so that an
inductor in its wireless charging receiver is in a magnetic field
produced by a wireless charging transmitter 1212, which can receive
power from a power outlet, not shown.
[0133] Depending on whether the mobile device of FIG. 13 is
connected to adaptor 108 or is placed in the magnetic field of
transmitter 1212, the voltage regulator system (e.g., using
controller 1004) can set the input to regulator 1006 (which
receives voltage V.sub.BUS) to be connected to the output of the
adaptor or the output of the wireless charging receiver using one
or more switches. The controller can then control V.sub.BUS as
output by the adapter or the wireless charging receiver as
described above.
[0134] Compared to using two separate voltage regulator systems for
wired and wireless charging, using a singled voltage regulator
system that can be connected to either reduces the total system
Bill of Materials (BOM) and cost. This is possible even when an SC
regulator used for wired charging needs to operate at different N:M
SC ratios than an SC regulator used for wireless charging. For
example, a wired charging system can be optimized for a 3:1 SC
regulator (V.sub.BUS is close to 3.times.V.sub.BAT) while the
wireless charging system may be optimized for a 4:1 SC regulator
(V.sub.BUS is close to 4.times.V.sub.BAT). Instead of using a
separate 3:1 SC regulator and a separate 4:1 SC regulator, a single
reconfigurable SC regulator that supports both 3:1 and 4:1 can be
used.
[0135] In some embodiments, a voltage regulator system, such as
voltage regulator system 1002 shown in FIG. 10, can be implemented
as a single chip. The single chip can include a single die that
includes both a controller and a regulator as disclosed herein. The
single chip can include two or more dies where one die includes a
controller and another die includes a regulator. In other
embodiments, a voltage regulator system can include two or more
chips where one chip includes a controller and another chip
includes a regulator.
[0136] In some embodiments, a controller such as controller 1004
shown in FIG. 10, can be implemented as a software application
running on a hardware processor. The software application can be
stored in memory. The memory can be a non-transitory computer
readable medium, flash memory, a magnetic disk drive, an optical
drive, a programmable read-only memory (PROM), a read-only memory
(ROM), or any other memory or combination of memories. The software
can run on a hardware processor capable of executing computer
instructions or computer code. The hardware processor can be
implemented in any suitable hardware such as a microprocessor, a
micro-controller, an application specific integrated circuit
(ASIC), programmable logic array (PLA), field programmable gate
array (FPGA), or any other suitable circuit. In some embodiment,
the controller can be implemented in hardware using an application
specific integrated circuit (ASIC), programmable logic array (PLA),
field programmable gate array (FPGA), or any other suitable
circuit. In some embodiments, the controller can be synthesized
using hardware programming languages including Verilog, VHDL, and
Bluespec.
[0137] As such, those skilled in the art will appreciate that the
conception, upon which this disclosure is based, may readily be
utilized as a basis for the designing of other structures,
apparatuses, systems, and methods for carrying out the several
purposes of the disclosed subject matter. It is important,
therefore, that the claims be regarded as including such equivalent
constructions insofar as they do not depart from the spirit and
scope of the disclosed subject matter.
[0138] Although the disclosed subject matter has been described and
illustrated in the foregoing exemplary embodiments, it is
understood that the present disclosure has been made only by way of
example, and that numerous changes in the details of implementation
of the disclosed subject matter may be made without departing from
the spirit and scope of the disclosed subject matter, which is
limited only by the claims which follow.
* * * * *